DevTools: move test from styles/css-outline -> elements/styles/css-outline

This is a left-over after a bad rebaseline.

TBR=pfeldman

Review URL: https://codereview.chromium.org/221183003

git-svn-id: svn://svn.chromium.org/blink/trunk@170875 bbb929c8-8fbe-4397-9dbb-9b2b20218538